Easy Tsumeshogi Problem for Beginners - #091

The diagram shows a one-move tsume(checkmate) problem. It's your turn. You have nothing in hand. So you will have to move one of your pieces on the board to checkmate the King. Which piece should you move? The answer will be found in the comment.

For those who would like to solve the problems in the past, I'm placing the links to my bookmarks to them below;